The present invention generally relates to disk drives and, more particularly, to a method for installing a printed circuit board assembly on a base plate of the disk drive, as well as the corresponding structure used by this method of installation.
Conventional disk drives typically include a base plate and a cover that is detachably connected to the base plate to define a housing for various disk drive components. One or more data storage disks are generally mounted on a spindle which is interconnected with the base plate and/or cover so as to allow the data storage disk(s) to rotate relative to both the base plate and cover via a spindle motor. An actuator arm assembly (e.g., a single actuator arm, a plurality of actuator arms, an E-block with a plurality of actuator arm tips) is interconnected with the base plate and/or cover so as to allow the actuator arm assembly to move relative to both the base plate and cover in a controlled manner. This motion is either typically a pivoting or a linear motion.
A suspension or load beam may be provided for each data storage surface of each data storage disk. Typically each disk has two of such surfaces. All suspensions are appropriately attached to and extend away from the actuator arm assembly in the general direction of the data storage disk(s) during normal operations. A transducer, such as a read/write head, is disposed on the free end of each suspension for purposes of exchanging signals with the corresponding data storage disk. The position of the actuator arm assembly, and thereby each transducer, is controlled by a voice coil motor or the like which moves the actuator arm assembly to dispose the transducer(s) at the desired radial position relative to the corresponding data storage disk.
Another component of the disk drive is a printed circuit board assembly that includes a printed circuit board and an appropriate drive interface connector. The printed circuit board operatively interconnects various components of the disk drive with a central processing unit or the like. After the drive interface connector is attached to the printed circuit board, the printed circuit board assembly is generally affixed to the underside of the base plate of the disk drive using screws. Due to the precision required in handling and/or assembling a printed circuit board assembly, such circuit board assemblies are generally installed onto the base plate by hand (i.e. a person applies screws through the circuit board assembly to affix the circuit board to the base plate). In some instances, one screw is directed through the drive interface connector on both sides thereof to control movement of the drive interface connector away from the base plate. However, this also introduces an undesired strain in the drive interface connector.
Human assembly of disk drive components, including installing printed circuit board assemblies onto base plates of disk drives, offers several potential shortcomings to the assembly process in that circuit boards may not be consistently positioned in the same location from base plate to base plate of respective disk drives. Further, human assembly also allows for variation in the force or torque used to tighten screws against the circuit board assembly and into the base plate, thus inflicting potential strain and/or damage on the printed circuit board assembly. Conversely, the screws may not get fastened sufficiently tight, leaving the potential for variation in distance between a base plate and a respective circuit board assembly and/or undesired vibrations during normal disk drive operations. Relatedly, the more screws that are used to fix the printed circuit board assembly to the base plate, the longer the total assembly time is for the disk drive. The total assembly time obviously has an effect on the total cost of the disk drive. Therefore, it would be desirable to have a printed circuit board assembly and base plate of a configuration that facilitates the installation of the printed circuit board assembly on the base plate.
The present invention is generally directed to disk drives. More specifically, the present invention is generally directed to a printed circuit board assembly for use with a compatible base plate of a disk drive. This printed circuit board assembly desirably addresses potential malpositioning of the circuit board (with regard to the base plate) associated with installation errors due to human assembly. Accordingly, production and/or assembly of any appropriate type/configuration of a disk drive may benefit from installing a printed circuit board assembly of the invention into a disk drive in a manner described below. Each of the various aspects of the printed circuit board assembly associated with the present invention and to be discussed in more detail below generally include at least one printed circuit board and at least one drive interface connector generally for communication between the disk drive and a central processing unit or the like.
A first aspect of the present invention is embodied in a printed circuit board assembly that is interconnectable with a base plate of a disk drive. The circuit board assembly generally includes a printed circuit board having a first reference axis defining a longitudinal extent of the circuit board, and first and second major surfaces. Since printed circuit boards may be at least generally rectangular or card-shaped, the first and second major surfaces of the printed circuit board define the two surfaces that reflect the greatest surface area of the circuit board. First and second sides of the printed circuit board are at least generally longitudinally extending and laterally spaced relative to the first reference axis. Additionally, the printed circuit board has a first end and a second end that are longitudinally spaced from the first end relative to the first reference axis. Along with a printed circuit board, the printed circuit board assembly has a drive interface connector that is positioned at the first end of the printed circuit board. Additionally, first and second base plate interface bosses extend at least generally away relative to the first and second sides of the printed circuit board, respectively.
Various refinements exist regarding the features noted in relation to the subject first aspect of the present invention. Additional features may also be incorporated in the subject first aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. For instance, the base plate interface bosses are preferably attached to the drive interface connector. In other words, the first and second base plate interface bosses are preferably projections of the drive interface connector which protrude from surfaces of the drive interface connector and which may be substantially aligned with the respective first and second sides of the printed circuit board. Thus, the surfaces of the drive interface connector from which these base plate interface bosses project may be perpendicular to the major surfaces of the printed circuit board. Put another way, the drive interface connector generally includes a housing having first and second ends; accordingly, the first and second base plate interface bosses may be disposed on the respective first and second ends of the drive interface connector. These base plate interface bosses are preferably integrally formed with the housing. Simply as a matter of manufacturing preference, the housing of the drive interface connector and the base plate interface bosses may be formed from plastic or the like. Plastic is used, among other reasons, simply because it is inexpensive, durable, and easily formable to be compatible with the size of a corresponding printed circuit board.
Each of the base plate interface bosses generally includes an annular, peripheral wall having both an arcuate portion and a planar portion. This peripheral wall is preferably perpendicular to the respective surface of the printed circuit board assembly from which the wall projects. However, other arrangements of the peripheral wall that would assist in preventing movement of the printed circuit board assembly from the base plate upon installation are contemplated. For example, a frustoconical configuration of the base plate interface bosses is contemplated, wherein each peripheral wall tapers toward the respective surface of the printed circuit board assembly from which each boss protrudes.
The above-noted planar portion of the peripheral wall is generally disposed at an angle between about 15 degrees and about 45 degrees, and in one embodiment is about 23 degrees, relative to a vertical reference axis. This angle of disposition is generally oriented such that the second major surface of the printed circuit board projects toward the base plate of the recipient disk drive when the printed circuit board assembly is installed on the base plate, and the planar portion of each peripheral wall of the base plate interface bosses at least generally projects toward the second major surface of the printed circuit board. In addition, the planar portion of the peripheral wall preferably at least generally projects toward the second end of the printed circuit board assembly (that which is opposite the drive interface connector). The vertical reference axis, as mentioned above, can be described as an imaginary line that is perpendicular to both the first and second major surfaces of the printed circuit board.
The printed circuit board can include one or more alignment slots. A longitudinal extent of each of the alignment slots is generally substantially parallel to the longitudinal reference axis. These alignment slots each generally define an aperture spanning from the first major surface to the second major surface of the printed circuit board. Thus, a corresponding alignment pin(s) on the base plate can be directed within the respective alignment slot(s) during pivoting assemblage of a base plate assembly in a manner that will be discussed in more detail below.
A second aspect of the present invention includes a base plate assembly for a disk drive that includes a combination of the above-discussed printed circuit board assembly and a complimentarily designed base plate for receiving the printed circuit board assembly. The base plate assembly generally includes a first reference axis defining a longitudinal extent of the base plate assembly. The base plate has a top surface, a bottom surface, and first and second sides that are at least generally longitudinally extending and laterally spaced relative to the first reference axis. First and second ends of the base plate at least generally laterally extend and are longitudinally spaced relative to the first reference axis. The base plate of the base plate assembly also has first and second printed circuit board assembly mounting slots to receive an above-described printed circuit board assembly, which again generally includes a printed circuit board, a drive interface connector, and first and second base plate interface bosses. These mounting slots of the base plate are preferably concave such that the base plate interface bosses on the printed circuit board assembly may be directed therein.
Various refinements exist regarding the features noted in relation to the subject second aspect of the present invention. Other features may also be incorporated in the subject second aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. For instance, the printed circuit board assembly mounting slots are generally disposed at least generally proximate the first end of the base plate. The base plate interface bosses of the printed circuit board assembly are generally positioned in these mounting slots of the base plate. Preferably, the first and second printed circuit board assembly mounting slots are disposed on extensions of the respective first and second sides of the base plate toward the first end of the base plate, wherein these extensions are generally parallel with the first reference axis. A flat may be disposed above each of the printed circuit board assembly mounting slots. A xe2x80x9cflatxe2x80x9d herein describes a substantially planar stretch of a corresponding wall. Preferably, the flat that corresponds with each of the printed circuit board assembly mounting slots is contained within a reference plane that is at least generally perpendicular to the first and second major board surfaces of the printed circuit board. As such, the planar portion on each of the base plate interface bosses for the above-described printed circuit board assembly may be positioned against a corresponding flat to dispose the printed circuit board in a desired position relative to the base plate before directing the interface bosses into their corresponding mounting slot on the base plate.
At least a portion of each of the printed circuit board assembly mounting slots may be generally arcuately shaped. Preferably the arcuate shape of the mounting slots reflects radii of substantially equal magnitude from a common point of origin within the space defined by the wall of the mounting slot. In other word, the arcuately shaped mounting slots are preferably circle segments. Put another way, each of the printed circuit board assembly mounting slots generally includes an arcuate extent defined by a single radius that extend at least about 190 degrees relative to a central axis about which the mounting slots are positioned. Thus, each of the printed circuit board assembly mounting slots is also preferably at least generally concave such that each of the base plate interface bosses may be directed within the respective mounting slot. Accordingly, an axis of rotation about which the concave printed circuit board assembly mounting slots extend is generally parallel to the first end of the base plate and oriented to span from he first side of the base plate to the second side of the base plate.
In some variations of the second aspect, the wall of each of the printed circuit board assembly mounting slots defines a catch feature to limit vertical movement of the base plate interface boss of the printed circuit board assembly upon engagement of the boss with the mounting slot after the printed circuit board assembly has assumed its final position relative to the base plate. Each of the first and second printed circuit board assembly mounting slots may be generally defined by a slot wall. Accordingly, a portion of the slot wall of the first mounting slot can capture the first base plate interface boss therein, and a portion of the slot wall of the second mounting slot can capture the second base plate interface boss therein. To provide clearance for the initial positioning of the printed circuit board assembly at an angle relative to the base plate and the subsequent pivotal movement of the printed circuit board assembly about the rotational axis formed by the relationship of the mounting slots and the base plate interface bosses, the first end of the base plate can have a chamfer that extends at least from the first mounting slot to the second mounting slot.
The base plate interface bosses generally can prevent dissociative movement of the first end of the printed circuit board assembly from the base plate when installed. In other words, once the first end of the printed circuit board assembly is properly engaged into a cooperatively configured area of the base plate to the disk drive, the relationship between the base plate and the base plate interface bosses of the printed circuit board assembly restricts movement of the first end of the printed circuit board assembly. Put another way, the base plate interface bosses and the printed circuit board assembly mounting slots, in combination, generally form a structure for preventing significant vertical movement of the first end of the printed circuit board assembly from the base plate when installed. The base plate interface bosses generally include a way for pivotally installing the printed circuit board assembly on the base plate. Put another way, the base plate interface bosses of the printed circuit board assembly can generally be engaged with a cooperatively designed portion of the base plate and subsequently rotated or pivoted about an axis that is substantially aligned with an imaginary line extending between the first and second base plate interface bosses of the printed circuit board. The circuit board may also include a plurality of screw holes to affix the printed circuit board assembly to the base plate. However, preferably none of the plurality of screw holes extends through the drive interface connector. In other words, while screws or other appropriate fasteners known in the art may be utilized to assist in attaching the printed circuit board assembly to the base plate, such fasteners only have contact with the printed circuit board, and not the drive interface connector of the printed circuit board assembly.
Some variations of the base plate assembly of the second aspect include the printed circuit board having elongate spindle motor connection pads that are disposed on a major surface of the circuit board and are perpendicularly oriented to the second lateral reference axis. In such variations, the base plate includes corresponding spindle motor connection contacts designed and configured to operationally receive the spindle motor connection pads upon pivoting the printed circuit board into an installed position on the bottom surface of the base plate. In other words, pivoting the first end of the printed circuit board assembly about the rotational axis defined by the mounting slots of the base plate forms a cooperative engagement of the spindle motor connection pads with the spindle motor connection contacts. Similarly, some variations of the printer circuit board preferably have elongate flex cable connector pads which are disposed on a major surface of the circuit board and are perpendicularly oriented to the second lateral reference axis. In such variations, the base plate includes corresponding flex cable connection contacts designed and configured to operationally receive the flex cable connection pads upon pivoting of the printed circuit board into an installed position on the bottom surface of the base plate. Thus, pivoting the first end of the printed circuit board assembly at/near the first end of the base plate enables a cooperative engagement of the flex cable connector pads with the flex cable connector contacts. Put another way, the respective connection pads and corresponding connection contacts are preferably parallel with the first reference axis to allow for a sliding movement of the respective contacts along the respective pads as the printed circuit board assembly is pivoted into an installed position on the base plate. Those various features discussed above in relation to the first aspect of the present invention may be incorporated in variations of this second aspect of the present invention as well (and vice versa), and in the manner noted above.
A third aspect of the invention is embodied in a method of installing a printed circuit board assembly on a base plate. The method includes disposing the first end of the printed circuit board assembly against the base plate at an angle relative to the base plate assembly. The method further includes pivoting the second end of the printed circuit board assembly toward the base plate and at least generally about the first end of the printed circuit board assembly. In other words, an angle is formed by the first end of the printed circuit board assembly preferably contacting the first end of the base plate. This angle continually decreases as the second end of the printed circuit board assembly converges toward the bottom surface of the base plate.
Various refinements exist of the features noted in relation to the subject third aspect of the present invention. Further features may also be incorporated in the subject third aspect of the present invention as well. These refinements and additional features may exist individually or in any combination. For instance, the dispositioning of the printed circuit board assembly at an angle relative to the base plate before pivoting the printed circuit board assembly toward the base plate may include engaging a flat on each of a pair of mounting bosses on the printed circuit board assembly with a corresponding flat on the base plate. In one embodiment, the printed circuit board assembly is disposed at an angle of about 23 degrees relative to a vertical axis (stated another way, at an angle of about 67 degrees between the printed circuit board and the xe2x80x9cunderlying base platexe2x80x9d prior to pivoting the printed circuit board assembly into the desired final position relative to the base plate). In any case, these corresponding flats on the printed circuit board assembly and the base plate may also be used to direct or guide the above-noted mounting bosses on the printed circuit board assembly within a pair of mounting slots that are formed on the base plate. That is, the printed circuit board assembly may be maintained in a relatively constant angular orientation relative to the general extent of the base plate as the first end of the printed circuit board assembly is moved at least generally toward the base plate to fully seat the mounting bosses within the mounting slots, and including in an at least generally perpendicular manner to the general extent of base plate.
The third aspect may also include simultaneously locking the first end of the printed circuit board assembly to the base plate by the noted above-noted pivoting of the printed circuit board assembly into the installed position against the base plate. This locking of the printed circuit board assembly to the base plate may include restricting vertical movement of the first end of the printed circuit board assembly away from base plate by pivoting the printed circuit board assembly under a xe2x80x9ccatchxe2x80x9d or sorts. Other ways of fixing the printed circuit board assembly to the base plate may be utilized, including directing one or more screws through the printed circuit board and into the base plate. In one embodiment, none of these screws pass through a drive interface connector that may be disposed on the first end of the printed circuit board. Therefore, deflections of the drive interface connector in the xe2x80x9czxe2x80x9d dimension are limited without directing any screws therethrough and which may cause undesired strain in the drive interface connector housing.
Certain alignment features may be incorporated into the subject third aspect of the present invention. For instance, one or more alignment pins may be disposed on the surface of the base plate that interfaces with the printed circuit board when fully installed. In this regard, a corresponding number of alignment slots may be included on the printed circuit board. Generally, any such alignment slot would be elongated in a direction that is at least generally parallel with the direction of the pivoting motion of the printed circuit board assembly during installation of the same to the base plate. Corresponding electrical contacts on the printed circuit board assembly and base plate may also be disposed so as to also be at least generally parallel with the direction of the pivoting motion of the printed circuit board assembly.